Sulfurized lubricant



Filed Aug. 2, 1948 Patented Mar. 20,:Y 1951 sULFURIzED LUBRICANT George N. Cade, Bartlesville, Okla., assigner `to Phillipsl Petroleum Company, a corporation of Delaware Application August 2, 1948, seri-a1 No. 42,1077v 8 Claims. I

This invention relates to the production of lubricant additives. More particularly', it relates to the production'oi additives that increase the lm strength of lubricating oils. In a more specific aspect, it relates to the conversion of a Waste by-product into an additive for lubricating oils, cutting oils, and the like.

In the production of hydrocarbon fuels for internal combustion engines by the alkylation of .parains with olens in the presence of liquid alkylation catalysts, .the catalysts gradually become diluted with comparatively high-boiling organic acid-soluble by-products. When other hydrocarbon conversions,.su ch as isomerization and disproportionation of paraiiins, are conducted in the presence of liquid Valkylation or Friedel-Crafts type catalysts, the catalysts gradually become diluted and deactivated With organic by-products similar to those obtained in alkylation. These In accordance with this invention, catalystsoluble by-products of the type previously mentioned are converted to useful materials by reaction With elemental sulfur at elevated temperatures. The sulfurized products obtained are useful as additives for lubricating oils, cutting oils, `and the like. When'blended with mineral lubri- Dilution of the catalyst with Water, hy- "1 eating oil they increase the film strength of the y The organic by-products sulfurizyed invaccordance with this invention are obtained as undesired catalyst diluents when hydrocarbon conversions,

such as paraiIin-olen alkylation, are conducted in the presence of liquid catalysts such as concentrated hydrouoric acid, concentrated sulfuric acid, concentrated phosphoric acid, halosulfonic terial is preferred because itis readily recoverable-by fractional distillation of the used catalyst. This material is commonly termed acid-soluble oi-l. 'It is to be understood, however, that the catalyst-soluble diluents or oils recoverable from other catalysts of the type previously discussed may be used Within the broadest scope of this invention. f f

The following properties are given as more or less typical of the acid-solubleoil produced `when isobutane is alkylated at about F. with -rerinery olerlns, mainly butenes, in the `presence of hydrofluoric acid having a titratable acidity of about 85 to 90 Weight per cent:

A. P. I. gravity l5-30 'Iodine number 1.10-260 Fluorine, Weight per cent 2 Sulfur, weight per cent 1 Total solids, Weight per cent 35-80 Viscosity at 210 F., S'. U. S 60-300 Aniline point, F 122-212 Flash point, F., C. O. C 190-230 Fire point, F., C. O. C 220-240 Pour point, F 5-80 A. S. T. M. distillation (vacuum), volume per cent distilled, F. (corr.)

First drop 220 10 546 '50 627 7.0 v(oil cracked) 640 Viscosity index of a fraction boiling above 574 F. (corr.) -61 "As indicated in the preceding tabulation, some of the properties vary from sample to sample, depending on speci'c conditions of acid fractionation, feedv composition, etc.

The catalyst-soluble oil is preferablyl reacted with sulfur vat about 180 to 400 F'. `for 1 to 10 hours. The reaction mixture is preferably con-- stantly stirred or otherwise agitated. The sulfur is preferably used in the finely divided solid or in itl-1e molten state. The amount of vsulfur added is approximately 5 to 50 Weight per cent, preferably 20 to 40 Weight per cent, of the catalyst- Asoluble oil. The reactionproductris stripped with steam, nitrogen, methane, or other inert gas to remove hydrogen sulfide formed. The stripping gas may be continuously contacted' with the oil and the sulfur during the reaction. In some cases, the reaction may be promoted With small amounts of sulfur halides. vThe sulfurized product contains from 5 to 35 Weight per cent of combined sulfur.` The exact percentage of combined sulfur in the product will dependupon several duit 23 to reaction zone 2I. lticularly when the amount of sulfur dioxide in factors, such as the amount of sulfur added, temperature employed, etc.

The accompanying drawing illustrates one method for practicing the invention in connection with a process for alkylating an isoparain with one or more oleiins in the presence of concentrated hydrofluoric acid. Commercial hydrofluoric acid containing small but undesirable amounts of sulfur dioxide enters treating zone 4 through inlet 2. Hydrogen sulfide enters the treating zone through inlet 3. In treating zone 4, the hydrogen sulfide reacts with the sulfur dioxide in accordance with the equation The molecular proportions of hydrogen sulfide and sulfui dioxide charged to treating zone 4 are approximately those indicated by this equation. The resulting mixture of hydrouoric acid, water, and sulfur is passed through conduit 5 to sulfur removal Zone 6.

Sulfur removal Zone 6 comprises one or more fractional distillation or ashing steps. A major fraction comprising chiey hydroiiuoric acid substantially free from sulfur compounds and Water is removed through conduit l, condensed in condenser 8, and passed to alkylation zone I0. A fraction comprising an azeotropic mixture of water and hydrouoric acid is withdrawn from the system through outlet 22. A residue comprising elemental sulfur is passed through con- In some cases, parthe hydrofluoric acid is unusually low, the recovery of the sulfur formed may be uneconomical. In such a case, the valve in conduit 23 is closed, and the sulfur formed in treating zone 4 is withdrawn through conduit 22 together with the aqueous hydrofluoric acid. The removal of sulfur dioxide by reaction with hydrogen sulfide is disclosed and claimed by M. P. Matuszak in U. S. Patent 2,414,884, granted January 28, 1947.

In alkylation zone I0, the hydrofluoric acid entering through conduit 'I is intimately mixed with hydrocarbon feed, Which enters through conduit S. The hydrocarbon feed comprises, for example, at least one olefin having at least three carbon atoms per molecule and at least a fourfold molar excess (based on total olefins) of isoparaffin. Alkylation conditions maintained in alkylation zone IU are those well known in the art for alkylating isoparaiins with olefins in the presence of hydrouoric acid, and no detailed discussion of these conditions is deemed necessary in this application.

lThe alkylation eiuent passes through conduit I I to settling Zone I2, in which the acid and the hydrocarbon phase separate. The hydrocarbon phase is Withdrawn through conduit I3 to a .fractional-distillation and alkylate recovery system not shown. The acid phase is recycled in -usually at least two. A major fraction comprising purified hydrofluoric acid is withdrawn through conduit I1 and recycled through conduit I5 to alkylation zone I0. A fraction comprising an azeotropic mixture of Water and hydrouoric acid is withdrawn from the system through conduit I8. A heavy, acid-soluble oil is withdrawn, as a distillation residue, through:

conduit I9. It has been customary in the past to discard the acid-soluble oil, as through outlet 20, but it is with this acid-soluble oil that the present invention is primarily concerned.

In accordance with this invention, the acidsoluble oil is passed, at least in part, through conduit I9 to reaction Zone 2I. Sulfur recovered in sulfur removal zone' E enters reaction zone 2| through conduit 23. Additional sulfur is added, as needed, through inlet 24. The acid-soluble oil and the sulfur are thoroughly mixed and heated in reaction zone 2I under conditions disclosed hereinbefore. The sulfurized oil produced in reaction zone 2I by the reaction of sulfur with the acid-soluble oil is Withdrawn through outlet 21. This reaction produces hydrogen sulfide as a byproduct. The hydrogen sulfide may be withdrawn through outlet 25, but is preferably recycyled, at least in part, to treating zone l through conduit 2B. Since the hydrogen sulfide is produced in comparatively high concentration in reaction zone 2|, it is advantageously utilized in treating zone 4 to remove sulfur dioxide from the influent commercial hydrouoric acid. Any additional hydrogen sulfide needed is added through inlet 3 from an outside source not shown.

The sulfurized oil withdrawn through outlet 2'! may be blended with a mineral lubricating oil to obtain a product lubricant having increased film strength and extreme pressure properties. The proportion of sulfurized oil added is sufficient to obtain a product oil containing about 1 to 10 Weight per cent of the sulfurized oil.

Example An acid-soluble oil recovered by distillation of hydrofluoric acid catalyst from an alkylation system in which isobutane was alkylated with butenes was reacted with finely divided elemental sulfur at 194-212 F. for 5 hours. Thirtythree grams of the acid-soluble oil and 11 grams of sulfur were used, and the mixture was continually stirred. After the 5-hour reaction period, methane was passed through the mixture at the reaction temperature for 2 hours to remove hydrogen sulfide.

The sulfurized oil obtained was blended with an S. A. E. 40 motor oil to obtain a product oil containing 1.0 Weight per cent of the sulfurized additive oil. The additive-containing oil and the additive-free S. A. E. 40 oil Were tested for film strength on an Almen testing machine. The oil containing the sulfurized acid-soluble oil Was found to have higher lm strength than the additive-free oil.

Higher proportions (e. g. 2 to 5 weight per cent) of the sulfurized acid-soluble oil further improve the extreme pressure properties of the S. A. E. 40 oil. v v

1. A method for preparing an additive for lubricating oils, which comprises lreacting in a reaction zone a hydrofiuoric acid-soluble oil with from 5 to 50 weight per cent of elemental sulfur based on said hydroluoric acid-soluble oil, said hydrofluoric acid-soluble oil being obtained from an alkylation process' wherein an alkylatable paraffin is alkylated with an olen in the presence of hydrouoric acid as a catalyst, maintain- .ing improved extreme pressure characteristics to lubricating oils when blended therewith.

2. A method which comprises reacting in a reaction zone a catalyst-soluble' oil with from 5 to 50 weight per cent of elemental sulfur based on said catalyst-soluble oil, said catalyst-soluble oil being obtained from a catalytic alkylation process wherein an alkylatable paraiin is caused to react with an'olen in the presence of an alkylation catalyst selected from the group consisting of sulfuric acid, hydrofluoric acid, phosphoric acid,l and an aluminum halidehydrocarbon complex, maintaining a temperature in said reaction zone in the range of 180-400 F. for a period of time in the range of one toten hours, and recovering a resulting sulfurized oil as.

a product of the process.

3. A process for preparing an additive for lubricating oils, which comprises reacting in a reaction zone a sulfuric acid-soluble oil with from 5 to 50 weight per cent of elemental sulfur based on said sulfuric acid-soluble oil, said sulfuric acidsoluble oil being obtained from an alkylation process wherein an alkylatable parafn is alkylated with an olefin in the presence of sulfuric acid as a catalyst, maintaining a temperature in said reaction zone in the range between 180-400" F. for a period of time in the range of from one to ten hours, and recovering a resulting sulfurized oil capable of imparting improved extreme pressure characteristics to lubricating oils when blended therewith.

4. In a process for preparing an additive for lubricating oils, which comprises reacting in a reaction zone an aluminum halide-hydrocarbon complex-soluble oil with from 5 to 50 weight per cent of elemental sulfur based on said aluminum halide-hydrocarbon complex-soluble oil, said aluminum halide-hydrocarbon complex-soluble oil being obtained by the hydrolysis of an aluminum halide-hydrocarbon complex that has been used to catalyze an alkylation process wherein an alkylatable paraffin is alkylated with an olen, maintaining a temperature in said reaction zone in the range between 180-400 F. for a period of time in the range of from one to ten hours, and

y recovering a resulting sulfurized oil capable of imparting improved extreme pressure characteristics to lubricating oils when blended therewith.

5. A process for preparing an additive for 1ubricating oils, which comprises reacting in a reaction zone a hydrofluoric acid-soluble oil. with elemental sulfur, said hydrofluoric acid-soluble oil being obtained from an alkylation process wherein an alkylatable paraiin is alkylated with an olefin in the presence of hydrouoric acid as a catalyst, maintaining a temperature in said reaction zone in the range of 180-400" F. thereby producing a sulfurized oil and hydrogen sulde, treating the fresh hydrofiuoric acid alkylation catalyst with at least a portion of said hydrogen sulde to reduce the sulfur dioxide contained in said hydroiiuoric acid catalyst to elemental sulfur, and reacting said elemental sulfur with said hydrofluoric acid-soluble oil.

6. A process for preparing `an additive for lu-` bricating oils, which comprises reacting in a reaction zone a hydroiiuoric acid-soluble oil with elemental sulfur, said hydrofluoric acid-soluble oil being obtained as a kettle product when hydrouoric acid that has been used to catalyze the alkylation of an alkylatable paraiiin lspuriied by distillation, maintaining a temperature in said reaction zone in the range of 180-400 F. thereby producing a sulfurized oil and hydrogen sulde, and treating the fresh hydrofluoric acid alkylation catalyst with at least a portion of said hydrogen sulfide to reduce the sulfur dioxide contained in said hydroiiuoric acid catalyst to elemental sulfur.

7. A method for preparing an additive for 1ubricating oils, which comprises reacting in a reaction zo-ne a hydroiiuoric acid-soluble oil with from 5 to 50 weight per cent of elemental sulfur based on said hydrofluoric acid-soluble oil, said hydrouoric acid-soluble oil being obtained from anralkylation process wherein isobutane is alkylated with butene in the presence of concentrated hydrouoric acid, said hydroiluoric acidsoluble oil possessing the following properties:

Gravity, A. P. I. 15-30 Iodine number 110-260 Aniline point, F 122-212 A. S. T. M. distillation (vacuum) volume per cent distilled, F. (corrected) First drop 220 10 546 627 (oil cracked) 640 maintaining a temperature in said reaction zone in the range from 18o-400 F. for a period of time in the range of from one to ten. hours, and recovering a resulting sulfurized oil as a product of the process.

8. A process for simultaneously producing a parainic hydrocarbon material useful as an ingredient for motor fuel and a lubricating oil additive, which comprises reacting isobutane with butenes in the presence of hydrofluoric acid catalyst in an alkylation zone maintained at reaction conditions, separating the effluent reaction mixture from said alkylation zone into an acid phase and a hydrocarbon phase, recovering from said acid phase an acid-soluble oil, reacting at least a portion of said acid-soluble oil in a reaction zone maintained at a temperature in the range between 180 and 400 F. with 5 to 50 weight per cent elemental sulfur based on the acid-soluble oil, thereby producing hydrogen sulfide and a sulfurized oil, treating the fresh hydrouoric acid alkylation catalyst with at least a portion of said hydro-gen sulfide, thereby converting said hydrogen sulde and sulfur dioxide contained in said hydrouoric acid catalyst to elemental sulfur and water, removing said elemental sulfur from the4 resulting reaction mixture and passing said elemental sulfur to said reaction zone.

GEORGE N. CADE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,218,132 Lincoln Oct. 15, 1940 2,246,282 Zimmer Junel'?, 1941 2,312,750 Cohen Mar. 2, 1943 2,330,858 Anderson Oct. 5, 1943 

1. A METHOD OF PREPARING AN ADDITIVE FOR LUBRICATING OILS, WHICH COMPRISES REACTING IN A REACTION ZONE A HYDROFLUORIC ACID-SOLUBLE OIL WITH FROM 5 TO 50 WEIGHT PER CENT OF ELEMENT SULFUR BASED ON SAID HYDROFLUORIC ACID-SOLUBEL OIL, SAID HYDROFLUORIC ACID-SOLUBLE OIL BEING OBTAINED FROM AN ALKYLATION PROCESS WHEREIN AN ALKYLATABLE PARAFFIN IS ALKYLATED WITH AN OLEFIN IN THE PRESENCE OF HYDROFLUORIC ACID AS A CATALYST, MAINTAINING A TEMPERATURE IN SAID REACTION ZONE IN THE RANGE BETWEEN 180-400* F. FOR A PERIOD OF TIME IN THE RANGE OF FROM ONE TO TEN HOURS, AND RECOVERING A RESULTING SULFURIZED OIL CAPABLE OF IMPARTING IMPROVED EXTREME PRESSURE CHARACTERISTICS TO LUBRICATING OILS WHEN BLENDED THEREWITH. 